# python中的多态不关心方法的继承关系，它们只关心签名
class Person:
    def eat(self):
        print("人吃五谷杂粮")


class Cat:
    def eat(self):
        print("猫吃小鱼")


class Dog:
    def eat(self):
        print("小狗爱吃骨头")


def fun(obj):
    obj.eat()


person = Person()
cat = Cat()
dog = Dog()

fun(person)
fun(cat)
fun(dog)
